Solution Preview

(1) Briefly describe three situations in which the First In First Out discipline rule is not applicable in queuing analysis.

There are several ways to organize queues:
1) FIFO (First In First Out) also called FCFS (First Come First Serve) - orderly queue.
2) LIFO (Last In First Out) also called LCFS (Last Come First Serve) - stack.
3) SIRO (Serve In Random Order).
4) Priority Queue that may be viewed as a number of queues for various priorities.

Here are some examples of non-FIFO queues:

* Hospital emergency room. The sickest people are seen first, even if they just got to the ER. This is an example of a priority queue.
* Any scenario where the order that you're seen is determined by a random lottery. This would be SIRO.
* LIFO is used in accounting sometimes (http://www.bellaonline.com/articles/art51668.asp).
* In ...